Shouldn't economies of scale dictate that the average price per person should go down (inflation-adjusted) rather than up though? I understand that adding capacity to support 9 million people and modern appliances over 17 years is a significant cost but when you average it down per capita I'd have believed that increases in productivity and technology would drive that figure down, not up.

I was going to suggest that the original hydro and nuclear has lower costs than newer plant, but there doesn't seem to be any hydro and nuclear is small so I can't say.

Not necessarily. Electricity is driven by peak demand, and adding capacity takes time and is expensive.

Energy prices have outpaced inflation in that time frame despite productivity gains.